Cement compositions with improved fluid loss characteristics and methods of cementing in surface and subterranean applications

ABSTRACT

The present invention provides cement compositions comprising an improved fluid loss control additive, and methods for cementing using such cement compositions. Exemplary embodiments of the cement compositions comprise a hydraulic cement, water, and a fluid loss control additive comprising an acrylamide copolymer derivative, a dispersant, and a hydratable polymer. Optionally, other additives suitable for inclusion in cement compositions may be added.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to cementing operations, and moreparticularly, to cement compositions comprising an improved fluid losscontrol additive, and methods of using such compositions in surface andsubterranean applications.

[0003] 2. Description of the Prior Art

[0004] Hydraulic cement compositions are commonly utilized insubterranean operations, particularly subterranean well completion andremedial operations. For example, hydraulic cement compositions are usedin primary cementing operations whereby pipe strings such as casings andliners are cemented in well bores. In performing primary cementing,hydraulic cement compositions are pumped into the annular space betweenthe walls of a well bore and the exterior surface of the pipe stringdisposed therein. The cement composition is permitted to set in theannular space, thereby forming an annular sheath of hardenedsubstantially impermeable cement therein that substantially supports andpositions the pipe string in the well bore and bonds the exteriorsurface of the pipe string to the walls of the well bore. Hydrauliccement compositions also are used in remedial cementing operations suchas plugging highly permeable zones or fractures in well bores, pluggingcracks and holes in pipe strings, and the like.

[0005] In order for such well cementing operations to be successful, thecement compositions utilized must include a fluid loss control additiveto reduce the loss of fluid, e.g., water, from the cement compositionswhen they contact permeable subterranean formations and zones. Excessivefluid loss, inter alia, causes a cement composition to be prematurelydehydrated, which limits the amount of cement composition that can bepumped, decreases the compressive strength of the cement composition,and prevents or reduces bond strength between the set cement compositionand the subterranean zone, the walls of pipe, and/or the walls of thewell bore. Fluid loss control agents may also be used in surface cementcompositions.

[0006] Conventional contemporary synthetic fluid loss control additivesare large, water-soluble polymers that are capable of functioning at awider range of temperatures. An example of such synthetic fluid losscontrol additive is a fluid loss additive consisting of hydrolyzedcopolymers of acrylamide (“AA”) and 2-acrylamido, 2-methyl propanesulfonic acid (“AMPS”). However, certain of these AA/AMPS copolymers areuseful only in operations where the bottom hole circulating temperature(“BHCT”) ranges from about 90° F. to about 125° F., whereas BHCT rangesencountered in such operations are often outside such a range. Stillfurther, certain of these copolymers have a salt tolerance of only up toabout 10%.

[0007] The temperature limitations of certain of the AA/AMPS copolymers,e.g., ineffectiveness at temperatures above about 125° F. BHCT, arebelieved to be the result of hydrolysis of the amide groups. Thecarboxylate groups formed by such hydrolysis convert the copolymers tomaterials which function to retard the setting of the cement and toreduce the compressive strength of the set cement. Further, in the lowerportion of the above-mentioned temperature range (between about 90° F.to about 100° F.) certain of the AA/AMPS copolymers are less effectiveas a fluid loss additive, requiring inclusion of larger amounts of suchadditive than at higher temperatures. The inclusion of a sufficientlylarge amount of a fluid loss control additive, to create a cementcomposition with acceptable fluid loss often creates viscosity andpumpability problems, since the addition of such copolymer directlyaffects the resultant slurry rheology. Certain copolymers of acrylamideand AMPS exhibit high viscosity and poor mixability, resulting in cementslurries having poor pumpability characteristics during cementingoperations. Mixability is a subjective term used to describe how wellthe components in the cement composition wet and mix with each other, aswell as the energy required to create a generally homogeneous slurry.

SUMMARY OF THE INVENTION

[0008] The present invention relates to cementing operations, and moreparticularly, to cement compositions comprising an improved fluid losscontrol additive, and methods of using such compositions in surface andsubterranean applications.

[0009] One method of the present invention comprises the steps ofproviding a cement composition comprising a hydraulic cement, water, anda fluid loss control additive comprising an acrylamide copolymerderivative, a dispersant, and a hydratable polymer; placing the cementcomposition into the subterranean formation; and permitting the cementcomposition to set therein.

[0010] One exemplary embodiment of the cement compositions of thepresent invention comprises a hydraulic cement, water, and a fluid losscontrol additive comprising an acrylamide copolymer derivative, adispersant and a hydratable polymer. Optionally, other additivessuitable for inclusion in cement compositions may be added.

[0011] The objects, features and advantages of the present inventionwill be readily apparent to those skilled in the art upon a reading ofthe description of the preferred embodiments, which follows.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0012] The present invention relates to cementing operations, and moreparticularly, to cement compositions comprising an improved fluid losscontrol additive, and methods of using such compositions in surface andsubterranean applications. While the compositions and methods of thepresent invention are useful in a variety of applications, they areparticularly useful for subterranean well completion and remedialoperations, such as primary cementing, e.g., cementing casings andliners in well bores, including those in production wells, which includemulti-lateral subterranean wells. They are also useful for surfacecementing operations, including construction cementing operations.

[0013] The cement compositions of the present invention generallycomprise a cement, water sufficient to form a pumpable slurry, and afluid loss control additive of the present invention. A wide variety ofoptional additives may be included, in the cement compositions of thepresent invention if desired. The cement compositions of the presentinvention may range in density from about 5 lb/gallon to about 30lb/gallon. In one embodiment, the cement compositions of the presentinvention range in density from about 8 lb/gallon to about 20 lb/gallon.

[0014] Any cements suitable for use in subterranean applications aresuitable for use in the present invention. Furthermore, any cementssuitable for use in surface applications, e.g., construction cements,are suitable for use in the present invention. In one embodiment, theimproved cement compositions of the present invention comprise ahydraulic cement. A variety of hydraulic cements are suitable for useincluding those comprised of calcium, aluminum, silicon, oxygen, and/orsulfur, which set and harden by reaction with water. Such hydrauliccements include, but are not limited to, Portland cements, pozzolanacements, gypsum cements, high alumina content cements, silica cements,and high alkalinity cements.

[0015] The water present in the cement compositions of the presentinvention may be from any source provided that it does not contain anexcess of compounds that adversely affect other compounds in the cementcompositions. For example, a cement composition of the present inventioncan comprise fresh water, salt water (e.g., water containing one or moresalts dissolved therein), brine (e.g., saturated salt water), orseawater. The water may be present in an amount sufficient to form apumpable slurry. Generally, the water is present in the cementcompositions of the present invention in an amount in the range of fromabout 15% to about 200% by weight of cement (“bwoc”) therein. In certainembodiments, the water is present in the cement compositions of thepresent invention in an amount in the range of from about 25% to about60% bwoc therein.

[0016] The improved fluid loss control additives of the presentinvention generally comprise an acrylamide copolymer derivative, ahydratable polymer, and a dispersant. Certain embodiments comprise anacrylamide copolymer derivative and a hydratable polymer. Certain otherembodiments comprise an acrylamide copolymer derivative and adispersant. Optionally, other additives may be added, such as, forexample, a zeolite, iron chloride, an organic acid, and the like.

[0017] The fluid loss additives of the present invention comprise anacrylamide copolymer derivative. As referred to herein, the term“copolymer” will be understood to mean a polymer comprising a pluralityof compounds. For example, a “copolymer” may comprise, inter alia, agraft polymer wherein one monomer is grafted onto a backbone comprisinganother monomer. Any compound comprising 2-acrylamido-2-methylpropanesulfonic acid, or acid salts thereof, will be an “acrylamide copolymerderivative” as that term is used herein. An example of a suitableacrylamide copolymer derivative comprises a copolymer, or copolymersalt, of N,N-dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid, or acid salts thereof. Another example of a suitableacrylamide copolymer derivative comprises a graft polymer comprising abackbone comprising at least one member selected from the groupconsisting of lignin, lignite and their salts, and a grafted pendantgroup comprising at least one member selected from the group consistingof 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals. Anotherexample of a suitable acrylamide copolymer derivative comprises a graftpolymer comprising a backbone comprising at least one member selectedfrom the group consisting of derivatized cellulose, polyvinyl alcohol,polyethylene oxide, polypropylene oxide, and a grafted pendant groupcomprising at least one member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals. Such examplesof suitable acrylamide copolymer derivatives are described in U.S. Pat.Nos. 4,015,991; 4,515,635; 4,555,269; 4,676,317; 4,703,801; and6,268,406, the relevant disclosures of which are incorporated herein byreference. An additional example of a suitable acrylamide copolymerderivative comprises copolymers or copolymer salts comprising2-acrylamido-2-methylpropane sulfonic acid or acid salts thereof; forexample, wherein the copolymers or copolymer salts comprise copolymersof hydrolyzed acrylamide and 2-acrylamido-2-methylpropane sulfonic acidderivatives. Examples of suitable commercially available acrylamidecopolymer derivatives include, inter alia, those commercially availablefrom Halliburton Energy Services, Inc., of Duncan, Okla., under thetradenames “HALAD®-344”; “HALAD®-413”; “HALAD®-4” and “HALAD®-700”. Incertain embodiments where the acrylamide copolymer derivative comprisesa copolymer or copolymer salt of N,N-dimethylacrylamide and2-acrylamido-2-methylpropane sulfonic acid or acid salts thereof, thecopolymer, or copolymer salt, may have a N,N-dimethylacrylamide to2-acrylamido-2-methylpropane sulfonic acid (or acid salts thereof) moleratio of from about 1:4 to about 4:1. In certain embodiments, thecopolymer, or copolymer salt, may have a weight average molecular weightof between about 75,000 and about 300,000 daltons. Generally, theacrylamide copolymer derivative is present in the fluid loss controladditives of the present invention in an amount in the range of fromabout 1% to about 99% by weight. In one embodiment, the acrylamidecopolymer derivative is present in the fluid loss control additive in anamount in the range of from about 30% to about 60% by weight.

[0018] Certain embodiments of the fluid loss control additive of thepresent invention comprise a dispersant. Where present, the dispersantin the fluid loss control additive acts, inter alia, to control therheology of the cement composition and to stabilize the cementcomposition over a broad density range. While a variety of dispersantsknown to those skilled in the art may be used in accordance with thepresent invention, a preferred dispersant is a water-soluble polymerprepared by the caustic-catalyzed condensation of formaldehyde withacetone wherein the polymer contains sodium sulfate groups. Such apreferred dispersant is commercially available under the tradedesignation “CFR-3™” from Halliburton Energy Services, Inc., of Duncan,Okla. Another suitable dispersant is commercially available under thetrade designation “CFR-2™,” also from Halliburton Energy Services, Inc.,of Duncan, Okla. Another source of a suitable dispersant is amulti-purpose cement additive commercially available under the tradedesignation “UNIVERSAL CEMENT SYSTEMS™” from Halliburton EnergyServices, Inc., of Duncan, Okla.; such additive is disclosed in U.S.Pat. Nos. 5,749,418; 5,968,255; and 5,972,103, the relevant disclosuresof which are herein incorporated by reference. Generally, the dispersantis present in the fluid loss control additive in an amount sufficient toprevent gelation of the cement composition. In some embodiments, thedispersant is present in the fluid loss control additive in an amount inthe range of from about 25% to about 50% by weight. In one embodiment,the dispersant is present in the fluid loss control additive in anamount in the range of from about 30% to about 40% by weight.

[0019] Certain embodiments of the present invention comprise ahydratable polymer. Where present, the hydratable polymer in the fluidloss control additive acts, inter alia, to increase the viscosity of thecement composition in which the fluid loss control additive is used.Various hydratable polymers can be utilized in the fluid loss controladditive including, but not limited to, carboxymethylcellulose,hydroxyethylcellulose, carboxymethylhydroxyethylcellulose, vinylsulfonated polymers, and hydratable graft polymers. An example of asuitable hydratable polymer is a cellulose derivative commerciallyavailable from Dow Chemical Co., under the tradename “CARBOTRON 20.”Another source of a suitable hydratable polymer is a multi-purposecement additive commercially available under the trade designation“UNIVERSAL CEMENT SYSTEMS™” from Halliburton Energy Services, Inc., ofDuncan, Okla.; such additive is disclosed in U.S. Pat. Nos. 5,749,418;5,968,255; and 5,972,103, the relevant disclosures of which are hereinincorporated by reference. Where utilized, the hydratable polymer ispresent in the fluid loss control additive in an amount sufficient tocontribute a desired degree of viscosity to the cement composition.Generally, the hydratable polymer is present in the fluid loss controladditive in an amount in the range of from about 0.1% to about 15% byweight. In one embodiment, the hydratable polymer is present in thefluid loss control additive in an amount in the range of from about 1.0%to about 5% by weight.

[0020] Optionally, the fluid loss control additives of the presentinvention may comprise a zeolite. Where used, the zeolite functions,.inter alia, to improve the suspension of the fluid loss control additivein a cement slurry. The zeolite further comprises a mixture of chabaziteand amorphous silica. The chabazite is present in the zeolite in anamount in the range of from about 50% by weight to about 75% by weight.In certain preferred embodiments, the chabazite is present in thezeolite in an amount in the range of from about 65% by weight to about70% by weight. The amorphous silica is generally present in the zeolitein an amount in the range of from about 25% by weight to about 50% byweight. In certain preferred embodiments, the amorphous silica ispresent in the zeolite in an amount in the range of from about 30% byweight to about 35% by weight. An example of a suitable source ofzeolite is available from the C2C Zeolite Corporation of Calgary,Canada. Where used, the zeolite is generally present in the fluid losscontrol additive in an amount in the range of from about 0. 1% by weightto about 15% by weight. In certain embodiments, the zeolite is presentin the fluid loss control additive in an amount in the range of fromabout 3% by weight to about 7% by weight.

[0021] Optionally, in certain embodiments, the fluid loss controladditives of the present invention may comprise iron chloride. Whereused, the iron chloride may be ferrous chloride, ferric chloride, ormixtures thereof. The iron chloride functions, inter alia, incombination with other components which may be present, to aid thecement composition in hydrating in a predictable manner. Inter alia, theiron chloride component may also improve the compressive strength of thecement composition in which it is used. In one embodiment, the ironchloride used in the improved fluid loss control additives of thepresent invention is anhydrous ferric chloride. An example of a suitablesource of anhydrous ferric chloride is commercially available from BASFCorporation in Germany. Where used, the iron chloride is present in thefluid loss control additive in an amount sufficient to allow the cementto be suitable for the subterranean environment of the well beingcemented. More particularly, the iron chloride may be present in thefluid loss control additive in an amount in the range of from about 5%to about 25% by weight. In certain embodiments, the iron chloride may bepresent in the fluid loss control additive in an amount in the range offrom about 10% to about 15% by weight.

[0022] In some embodiments, the fluid loss control additive mayoptionally comprise an organic acid. Where present, the organic acidacts, inter alia, to maintain the viscosity of the cement composition inwhich the fluid loss control additive is used over a broad density rangeby helping to prevent gelation of the cement composition. Variousorganic acids can be utilized in the fluid loss control additiveincluding, but not limited to, tartaric acid, citric acid; gluconicacid, oleic acid, phosphoric acid, and uric acid. An example of asuitable organic acid is commercially available from Halliburton EnergyServices, Inc., of Duncan, Okla., under the tradename “HR®-25.” Otherexamples of suitable organic acids include, for example, organic acidswhich have either minimal or no effect on retarding or accelerating thesetting of the cement. One of ordinary skill in the art with the benefitof this disclosure will recognize the types of organic acids which areappropriate for inclusion in the improved fluid loss control additivesof the present invention. Where used, the organic acid is present in thefluid loss control additive in an amount sufficient to provide a desireddegree of viscosity control. Generally, the organic acid is present inthe fluid loss control additive in an amount in the range of from about0.01% to about 5% by weight. In one embodiment, the organic acid ispresent in the fluid loss control additive in an amount in the range offrom about 0.5% to about 2% by weight.

[0023] Optionally, the fluid loss control additive may contain adeaggregation agent. Where used, the deaggregation agent functions,inter alia, to improve the ability of the fluid loss control additive toflow freely as a powder. The deaggregation agent may also contribute aminor source of silica to the multi-purpose cement additive. An exampleof a suitable deaggregation agent is commercially available fromNational Pigment and Chemical Co. under the tradename Mica/Brite X150.Alternatively, quartz or ground sand may be used, though the sphericalnature of Mica/Brite X150 particles is thought to contribute to improvedflow characteristics for the cement composition. Generally, thedeaggregation agent is present in the fluid loss control additive in anamount sufficient to enable the fluid loss control additive to flowfreely as a powder. In some embodiments, the deaggregation agent ispresent in the fluid loss control additive in an amount in the range offrom about 1% to about 15% by weight. In one embodiment, thedeaggregation agent is present in the fluid loss control additive in anamount in the range of from about 5% to about 10% by weight.

[0024] Optionally, the fluid loss control additive may comprise a sourceof silica. Where present in the fluid loss control additive, the silicaassists in maintaining the compressive strength of the cementcomposition after setting. An example of a suitable source of highsurface area amorphous silica is commercially available from HalliburtonEnergy Services, Inc., of Duncan, Okla., under the tradename“SILICALITE.” Where used, the high surface area amorphous silica ispresent in the fluid loss control additive in an amount sufficient toprovide a desired after-set compressive strength. More particularly, thehigh surface area amorphous silica is present in the fluid loss controladditive in an amount in the range of from about 0.1% to about 15% byweight. In one embodiment, the high surface area amorphous silica ispresent in the fluid loss control additive in an amount in the range offrom about 1% to about 5% by weight.

[0025] The improved fluid loss control additives of the presentinvention may be prepared in a variety of forms, including, inter alia,particulates, solutions, suspensions. Generally, the fluid loss controladditives of the present invention are present in the cementcompositions of the present invention in an amount sufficient to providea desired level of fluid loss control. More particularly, the fluid losscontrol additive may be present in the cement composition in an amountin the range of from about 0.01% to about 10% bwoc. In certain preferredembodiments, the fluid loss control additive is present in the cementcomposition in an amount in the range of from about 0.25% to about 1.5%bwoc.

[0026] As will be recognized by those skilled in the art, the cementcompositions of this invention also can include additional suitableadditives, including, inter alia, accelerants, set retarders, defoamers,microspheres, fiber, weighting materials, salts, vitrified shale, flyash and the like. Any suitable additive may be incorporated within thecement compositions of the present invention. One of ordinary skill inthe art with the benefit of this disclosure will be able to recognizewhere a particular additive is suitable for a particular application.

[0027] An exemplary embodiment of a cement composition of the presentinvention comprises Class H Portland cement, 45% water bwoc, and 0.7%fluid loss control additive of the present invention bwoc. An exemplaryembodiment of a fluid loss control additive of the present inventioncomprises 63.1% acrylamide copolymer derivative, and 36.9% dispersant.Another exemplary embodiment of a fluid loss control additive of thepresent invention comprises 95.7% acrylamide copolymer derivative, and4.3% hydratable polymer.

[0028] A method of the present invention comprises providing a cementcomposition that comprises a cement, water sufficient to form a pumpableslurry, and a fluid loss control additive of the present invention;placing this cement composition in a subterranean formation; andpermitting the cement composition to set therein.

[0029] To facilitate a better understanding of the present invention,the following illustrative examples of some of the preferred exemplaryembodiments are given. In no way should such examples be read to limitthe scope of the invention.

EXAMPLE 1

[0030] Sample compositions were prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. Each samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 20 minutes at 125° F. in anatmospheric consistometer. After the sample was poured into a preheatedcell with a 325 mesh screen, a fluid loss test was performed for 30minutes at 1,000 psi and 125° F., in accordance with API RP 10B,Recommended Practices for Testing Well Cements.

[0031] Sample Composition No. 1 comprises a 15.6 lb/gallon (“ppg”)slurry of Texas Lehigh Class A cement, with no fluid loss additives. Thefluid loss was found to be 1,574 cubic centimeters.

[0032] Sample Composition No. 2 was prepared by mixing 0.5% of UniversalCement Systems™ multi-purpose cement additive by weight of cement with a15.6 ppg slurry of Texas Lehigh Class A cement. The fluid loss was foundto be 1,175 cubic centimeters.

[0033] Sample Composition No. 3 was prepared by mixing 0.35% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss was found to be 270cubic centimeters.

[0034] Sample Composition No. 4 was prepared by mixing 0.7% of a fluidloss control additive with a 15.8 ppg slurry of an experimental cementbearing compositional similarities to a Class H cement. The fluid losscontrol additive comprised a 1:1 mixture of an acrylamide copolymerderivative (HALAD®-344) and Universal Cement Systems™ multi-purposecement additive. Accordingly, Sample Composition No. 4 contained 0.35%HALAD®-344 by weight of cement and 0.35% Universal Cement Systems™multi-purpose cement additive by weight of cement. The fluid loss wasfound to be 112 cubic centimeters.

[0035] Sample Composition No. 5 was prepared by mixing 0.5% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss was found to be 80cubic centimeters.

[0036] A summary of the fluid loss demonstrated by each of the samplesis depicted in Table 1, below. TABLE 1 % Universal Cement % HALAD ®-FLUID FLUID Systems ™ 344 LOSS (cc) Sample Composition 0 0 1,574 No. 1Sample Composition 0.5 0 1,175 No. 2 Sample Composition 0 0.35 270 No. 3Sample Composition 0.35 0.35 112 No. 4 Sample Composition 0 0.5 80 No. 5

[0037] Thus, Example 1 demonstrates, inter alia, that the use of a fluidloss control additive comprising a reduced dose of an acrylamidecopolymer derivative delivers performance comparable to a larger dose ofan acrylamide copolymer derivative.

EXAMPLE 2

[0038] Sample Composition No. 4 was then permitted to age for a periodof two days, and a period of ten days. After each time period hadelapsed, a fluid loss test was again performed for 30 minutes at 1,000psi and 125° F. After aging for a total of two days, Sample CompositionNo. 4 demonstrated a fluid loss of 84 cubic centimeters. After aging fora total of ten days, Sample Composition No. 4 demonstrated a fluid lossof 76 cubic centimeters. This Example demonstrates, inter alia, that theuse of a fluid loss control additive comprising a reduced dose ofacrylamide copolymer derivative, can deliver performance equal to orsuperior to a larger dose of acrylamide copolymer derivative.

EXAMPLE 3

[0039] Sample compositions were prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. Each samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 20 minutes at 125° F. in anatmospheric consistometer. After the sample was poured into a preheatedcell with a 325 mesh screen, a fluid loss test was performed for 30minutes at 1,000 psi and 125° F., in accordance with API RP 10B,Recommended Practices for Testing Well Cements.

[0040] Sample Composition No. 6 was prepared by mixing 0.5% of anacrylamide copolymer derivative (HALAD®-413) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss was found to be 615cubic centimeters.

[0041] Sample Composition No. 7 was prepared by mixing a 15.8 ppg slurryof an experimental cement bearing compositional similarities to a Class.H cement with 1.0% of a fluid loss additive comprising a 1:1 mixture ofUniversal Cement Systems™ multi-purpose cement additive with anacrylamide copolymer derivative (HALAD®-413); accordingly, SampleComposition No. 7 contained 0.5% HALAD®-413 by weight of cement and 0.5%Universal Cement Systems™ multi-purpose cement additive by weight ofcement. The fluid loss was found to be 212 cubic centimeters.

[0042] Sample Composition No. 8 was prepared by mixing 0.7% of anacrylamide copolymer derivative (HALAD®-413) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss was found to be 188cubic centimeters.

[0043] Sample Composition No. 9 was prepared by mixing 0.5% of anacrylamide copolymer derivative (HALAD®-4) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss was found to be 196cubic centimeters.

[0044] Sample Composition No. 10 was prepared by mixing a 15.8 ppgslurry of an experimental cement bearing compositional similarities to aClass H cement with 1.0% of a fluid loss control additive comprising a1:1 mixture of Universal Cement Systems™ multi-purpose cement additiveand an acrylamide copolymer derivative (HALAD®-4); accordingly, SampleComposition No. 10 contained 0.5% HALAD®-4 by weight of cement and 0.5%Universal Cement Systems™ multi-purpose cement additive by weight ofcement. The fluid loss was found to be 100 cubic centimeters.

[0045] Sample Composition No. 11 was prepared by mixing 0.7% of anacrylamide copolymer derivative (HALAD®-4) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss was found to be 64cubic centimeters.

[0046] A summary of the fluid loss demonstrated by each of the samplesis depicted in Table 2, below. TABLE 2 % Universal % % FLUID CementHALAD ®- HALAD ®- LOSS FLUID Systems ™ 413 4 (cc) Sample 0 0.5 0 615Composition No. 6 Sample 0.5 0.5 0 212 Composition No. 7 Sample 0 0.7 0188 Composition No. 8 Sample 0 0 0.5 196 Composition No. 9 Sample 0.5 00.5 100 Composition No. 10 Sample 0 0 0.7 64 Composition No. 11

[0047] Universal Cement Systems™ multi-purpose cement additive comprisesa hydratable polymer and a dispersant. Example 3 demonstrates, interalia, that the use of an improved fluid loss control additive comprisinga hydratable polymer, a dispersant, and a reduced dose of an acrylamidecopolymer derivative provides comparable fluid loss control to a fluidloss control additive comprising a larger dose of an acrylamidecopolymer derivative. Inter alia, Example 3 also demonstrates that avariety of acrylamide copolymer derivatives are suitable for combinationwith, inter alia, a hydratable polymer and a dispersant, in the fluidloss control additives of the present invention.

EXAMPLE 4

[0048] Sample compositions were prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. Each samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 20 minutes at 190° F. in anatmospheric consistometer. After the sample was poured into a preheatedcell with a 325 mesh screen, a fluid loss test was performed per APISpecification 10.7 for 30 minutes at 1,000 psi and 205° F.

[0049] Sample Composition No. 12 was prepared by mixing 0.49% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss at 1,000 psi and 205°F. was found to be 220 cubic centimeters.

[0050] Sample Composition No. 13 was prepared by mixing 0.98% of a fluidloss control additive of the present invention with a 15.8 ppg slurry ofan experimental cement bearing compositional similarities to a Class Hcement. The fluid loss control additive comprised a 1:1 mixture ofUniversal Cement Systems™ multi-purpose cement additive and anacrylamide copolymer derivative (HALAD®-344); accordingly, SampleComposition No. 13 contained 0.49% HALAD®-344 by weight of cement and0.49% Universal Cement Systems™ multi-purpose cement additive by weightof cement. The fluid loss at 1,000 psi and 205° F. was found to be 60cubic centimeters.

[0051] Sample Composition No. 14 was prepared by mixing 0.7% of anacrylamide-copolymer derivative (HALAD®-344) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. The fluid loss at 1,000 psi and 205°F. was found to be 44 cubic centimeters.

[0052] A summary of the fluid loss demonstrated by each of the samplesis depicted in Table 3, below. TABLE 3 % Universal Cement % HALAD ®-FLUID FLUID Systems ™ 344 LOSS (cc) Sample 0 0.49 220 Composition No. 12Sample 0.49 0.49 60 Composition No. 13 Sample 0 0.7 44 Composition No.14

[0053] Thus, Example 4 demonstrates, inter alia, that the use of a fluidloss control additive comprising a reduced dose of an acrylamidecopolymer derivative delivers performance comparable to a larger dose ofan acrylamide copolymer derivative. Additionally, Example 4 demonstratesthat such fluid loss control additive is an effective fluid loss controladditive at elevated temperatures and pressures.

EXAMPLE 5

[0054] A sample composition was prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. The samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 60 minutes at 400° F. in a stirringfluid loss cell. After the sample was poured into a preheated cell witha 325 mesh screen, a fluid loss test was performed for 30 minutes at1,000 psi and 400° F.

[0055] Sample Composition No. 15 was prepared by mixing 0.84% of a fluidloss control additive of the present invention with a 15.6 ppg slurrycomprising 30% “SSA-1” bwoc, and the balance comprising an experimentalcement bearing compositional similarities to a Class H cement. SSA-1 isa silica flour additive available from Halliburton Energy Services,Inc., of Houston, Tex. The fluid loss control additive comprised a 1:1mixture of Universal Cement Systems™ multi-purpose cement additive andan acrylamide copolymer derivative (HALAD®-344); accordingly, SampleComposition No. 15 contained 0.42% HALAD®-344 by weight of cement and0.42% Universal Cement Systems™ multi-purpose cement additive by weightof cement. The fluid loss at 1,000 psi and 405° F. was found to be 400cubic centimeters.

[0056] Inter alia, Example 5 demonstrates that the fluid loss controladditive of the present invention provides fluid loss control atelevated temperatures.

EXAMPLE6

[0057] The transition time of a cement composition may be defined as thetime period starting when the cement composition has sufficient gelstrength to support itself yet cannot prevent influx of formationfluids, and ending when the cement composition achieves sufficient gelstrength to prevent the influx of such formation fluids. Experimentally,the transition time may be approximated by measuring the time period inwhich the gel strength of a cement composition progresses from about 100lb per 100 ft² to about 500 lb per 100 ft².

[0058] The zero-gel time, which may also be referred to as thedelayed-gel time, refers to the time period starting when the cementcomposition is placed in a subterranean formation and ending when thegel strength of the cement composition progresses to about 100 lb per100 ft², i.e., ending when the cement composition begins its transitiontime.

[0059] Sample compositions were prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. Each samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 40 minutes to 125° F. in a MiniMac®at 5,000 psi. Then, a static gel strength test was performed.

[0060] Sample Composition No. 16 was prepared by mixing 0.7% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement with a15.8 ppg slurry of an experimental cement bearing compositionalsimilarities to a Class H cement. Sample Composition No. 16 demonstrateda zero gel time of 41 minutes, and a transition time of 17 minutes.

[0061] Sample Composition No. 17 was prepared by mixing 1.0% of a fluidloss control additive of the present invention with a 15.8 ppg slurry ofan experimental cement bearing compositional similarities to a Class Hcement. The fluid loss control additive comprised a 1:1 mixture ofUniversal Cement Systems™ multi-purpose cement additive and anacrylamide copolymer derivative (HALAD®-344); accordingly, SampleComposition No. 17 contained 0.5% HALAD®-344 by weight of cement and0.5% Universal Cement Systems™ multi-purpose cement additive by weightof cement. Sample Composition No. 17 demonstrated a zero gel time of 1hour 16 minutes and a transition time of 17 minutes.

[0062] A summary of the data from each of the samples is depicted inTable 4, below. TABLE 4 % Universal % Transition Cement HALAD ®- ZeroGel Time Time FLUID Systems ™ 344 (hours:minutes) (minutes) Sample 0 0.70:41 17 Composition No. 16 Sample 0.5 0.5 1:16 17 Composition No. 17

[0063] Thus, Example 6 demonstrates, inter alia, that the use of a fluidloss control additive comprising a reduced dose of an acrylamidecopolymer derivative delivers performance comparable to a larger dose ofthe acrylamide copolymer derivative.

EXAMPLE 7

[0064] Sample compositions were prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. Each samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 20 minutes at 125° F. in anatmospheric consistometer. After the sample was poured into a preheatedcell with a 325 mesh screen, a fluid loss test was performed for 30minutes at 1,000 psi and 125° F., in accordance with API RP 10B,Recommended Practices for Testing Well Cements.

[0065] Sample Composition No. 18 was prepared by mixing 0.7% of a fluidloss additive by weight of cement with a 15.8 ppg slurry of anexperimental cement bearing compositional similarities to a Class Hcement. The fluid loss additive comprised a 1:1 mixture of UniversalCement Systems™ multi-purpose cement additive with an acrylamidecopolymer derivative (HALAD®-344); accordingly, Sample Composition No.18 contained 0.35% HALAD®-344 by weight of cement and 0.35% UniversalCement Systems™ multi-purpose cement additive by weight of cement. Thefluid loss was found to be 80 cubic centimeters.

[0066] Sample Composition No. 19 was prepared by mixing a 15.8 ppgslurry of an experimental cement bearing compositional similarities to aClass H cement with 0.7% of a fluid loss additive comprising 47.5% of anacrylamide copolymer derivative (HALAD®-344) by weight, 47.5% UniversalCement Systems™ multi-purpose cement additive by weight, and 5% zeoliteby weight. Accordingly, Sample Composition No. 19 contained 0.3325%HALAD®-344 by weight of cement, 0.3325% Universal Cement Systems™multi-purpose cement additive by weight of cement, and 0.035% zeolite byweight of cement. The fluid loss was found to be 96 cubic centimeters.

[0067] Thus, Example 7, demonstrates, inter alia, that the use of afluid loss control additive of the present invention provides acceptablefluid loss control.

EXAMPLE 8

[0068] Sample compositions were prepared by mixing a cement slurry witha fluid loss additive according to the following procedure. Each samplewas dry blended, then mixed for 35 seconds at 13,000 rpm in a blender.Next, the sample was conditioned for 20 minutes at 125° F. in anatmospheric consistometer. After the sample was poured into a preheatedcell with a 325 mesh screen, a fluid loss test was, performed for 30minutes at 1,000 psi and 125° F., in accordance with API RP 10B,Recommended Practices for Testing Well Cements.

[0069] Sample Composition No. 20 comprises a 15.8 ppg slurry of TXIClass H cement, with no fluid loss control additives. The fluid loss wasfound to be 1,529 cubic centimeters.

[0070] Sample Composition No. 21 was prepared by mixing 0.35% ofUniversal Cement Systems™ multi-purpose cement additive by weight ofcement with a 15.8 ppg slurry of TXI Class H cement. The fluid loss wasfound to be 1,343 cubic centimeters.

[0071] Sample Composition No. 22 was prepared by mixing. 0.35% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement with a15.8 ppg slurry of TXI Class H cement. The fluid loss was found to be 64cubic centimeters.

[0072] Sample Composition No. 23 was prepared by mixing 0.35% of an,acrylamide copolymer derivative (HALAD®-344) by weight of cement and0.0157% of a hydrated polymer (CARBOTRON 20) by weight of cement with a15.8 ppg slurry of TXI Class H cement. The fluid loss was found to be 60cubic centimeters.

[0073] Sample Composition No. 24 was prepared by mixing 0.35% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement,0.0157% of a hydrated polymer (CARBOTRON 20) by weight of cement, and0.204% of a dispersant (CFR-3) by weight of cement, with a 15.8 ppgslurry of TXI Class H cement. The fluid loss was found to be 44 cubiccentimeters.

[0074] Sample Composition No. 25 was prepared by mixing a 15.8 ppgslurry of TXI Class H cement with 0.7% of a fluid loss additivecomprising 47.5% of an acrylamide copolymer derivative (HALAD®-344) byweight, 47.5% Universal Cement Systems™ multi-purpose cement additive byweight, and 5% zeolite by weight. Accordingly, Sample Composition No. 25contained 0.3325% HALAD®-344 by weight of cement, 0.3325% UniversalCement Systems™ multi-purpose cement additive by weight of cement, and0.035% zeolite by weight of cement. The fluid loss was found to be 44cubic centimeters.

[0075] Sample Composition No. 26 was prepared by mixing 0.35% of anacrylamide copolymer derivative (HALAD®-344) by weight of cement and0.204% of a dispersant (CFR-3) by weight of cement, with a 15.8 ppgslurry of TXI Class H cement. The fluid loss was found to be 48 cubiccentimeters.

[0076] A summary of the data from each of the samples is depicted inTable 5, below. TABLE 5 % Universal % Cement % CARBOTRON FLUID FLUIDSystems ™ HALAD ® -344 % Zeolite 20 % CFR-3 LOSS (cc) Sample 0 0 0 0 01,529 Composition No. 20 Sample 0.35 0 0 0 0 1,343 Composition No. 21Sample 0 0.35 0 0 0 64 Composition No. 22 Sample 0 0.35 0 0.0157 0 60Composition No. 23 Sample 0 0.35 0 0.0157 0.204 44 Composition No. 24Sample 0.3325 0.33250 0.035 0 0 44 Composition No. 25 Sample 0 0.35 0 00.204 48 Composition No. 26

[0077] Inter alia, Example 8 demonstrates that the addition of, interalia, a zeolite, a hydratable polymer, and a dispersant, to anacrylamide copolymer derivative provide improved fluid loss control.

[0078] Therefore, the present invention is well adapted to carry out theobjects and attain the ends and advantages mentioned as well as thosethat are inherent therein. While numerous changes may be made by thoseskilled in the art, such changes are encompassed within the spirit ofthis invention as defined by the appended claims.

What is claimed is:
 1. A method of cementing in a subterranean formationcomprising the steps of: providing a cement composition comprising ahydraulic cement, water, and a fluid loss control additive, the fluidloss control additive comprising: an acrylamide copolymer derivative;and a hydratable polymer; placing the cement composition into thesubterranean formation; and permitting the cement composition to settherein.
 2. The method of claim 1 wherein the acrylamide copolymerderivative comprises a copolymer or copolymer salt ofN,N-dimethylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid oracid salts thereof.
 3. The method of claim 1 wherein the acrylamidecopolymer derivative comprises a graft polymer comprising a backbonecomprising at least one member selected from the group consisting oflignin, lignite and their salts and a grafted pendant group comprisingat least one member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 4. The methodof claim 1 wherein the acrylamide copolymer derivative comprises a graftpolymer comprising a backbone comprising at least one member selectedfrom the group consisting of derivatized cellulose, polyvinyl alcohol,polyethylene oxide, polypropylene oxide, and a grafted pendant groupcomprising at least one member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 5. The methodof claim 1 wherein the acrylamide copolymer derivative comprisescopolymers or copolymer salts comprising 2-acrylamido-2-methylpropanesulfonic acid or acid salts thereof.
 6. The method of claim 5 whereinthe copolymers or copolymer salts, comprise copolymers of hydrolyzedacrylamide and 2-acrylamido-2-methylpropane sulfonic acid derivatives.7. The method of claim 1 wherein the hydratable polymer comprisescarboxymethylcellulose, hydroxyethylcellulose,carboxymethylhydroxyethylcellulose, vinyl sulfonated polymers,hydratable graft polymers, and mixtures thereof.
 8. The method of claim1 wherein the fluid loss control additive further comprises adispersant.
 9. The method of claim 8 wherein the dispersant comprises awater-soluble polymer prepared by the caustic-catalyzed condensation offormaldehyde with acetone wherein the polymer contains sodium sulfategroups.
 10. The method of claim 1 wherein the fluid loss controladditive further comprises a zeolite.
 11. The method of claim 1 whereinthe fluid loss control additive further comprises a dispersant and azeolite.
 12. The method of claim 11 wherein the fluid loss controladditive further comprises iron chloride, an organic acid, adeaggregation agent, silica, or mixtures thereof.
 13. The method ofclaim 1 wherein the cement comprises Portland cements, pozzolaniccements, gypsum cements, high alumina content cements, silica cements,or high alkalinity cements.
 14. The method of claim 1 wherein the wateris present in the cement composition in an amount sufficient to form apumpable slurry.
 15. The method of claim 1 wherein the water is presentin the cement composition in an amount in the range of from about 15% toabout 200% by weight of cement.
 16. The method of claim 1 wherein thecement composition has a density in the range of from about 5 pounds pergallon to about 30 pounds per gallon.
 17. The method of claim 1 whereinthe cement composition further comprises a, weighting agent, a defoamer,a surfactant, mica, fiber, bentonite, microspheres, fumed silica, asalt, vitrified shale, fly ash, a dispersant, a retardant or anaccelerant.
 18. The method of claim 1 wherein the fluid loss controladditive is present in the cement composition in an amount sufficient toprovide a desired degree of fluid loss control.
 19. The method of claim1 wherein the fluid loss control additive is present in the cementcomposition in an amount in the range of from about 0.01% by weight ofcement to about 5.0% by weight of cement.
 20. The method of claim 12wherein the iron chloride is present in the fluid loss control additivein an amount sufficient to allow the cement to be suitable for thesubterranean temperature of the well being cemented.
 21. The method ofclaim 12 wherein the iron chloride is present in the fluid loss controladditive in an amount in the range of from about 5% to about 25% byweight of the fluid loss control additive.
 22. The method of claim 12wherein the iron chloride is anhydrous ferric chloride.
 23. The methodof claim 8 wherein the dispersant is present in the fluid loss controladditive in an amount sufficient to prevent gelation of the cementcomposition.
 24. The method of claim 8 wherein the dispersant is presentin the fluid loss control additive in an amount in the range of fromabout 25% to about 50% by weight of the fluid loss control additive. 25.The method of claim 1 wherein the hydratable polymer is present in thefluid loss control additive in an amount in the range of from about 0.1%to about 15% by weight of the fluid loss control additive.
 26. Themethod of claim 12 wherein the organic acid is) present in the fluidloss control additive in an amount sufficient to provide a desireddegree of viscosity control.
 27. The method of claim 12 wherein theorganic acid is present in the fluid loss control additive in an amountin the range of from about 0.01% to about 5% by weight of the fluid losscontrol additive.
 28. The method of claim 12 wherein the silica is highsurface area amorphous silica.
 29. The method of claim 12 wherein thede-aggregation agent is present in the fluid loss control additive in anamount sufficient to enable the fluid loss control additive to flowfreely as a powder.
 30. The method of claim 29 wherein thede-aggregation agent is present in the fluid loss control additive in anamount in the range of from about 1% to about 15% by weight of the fluidloss control additive.
 31. The method of claim 28 wherein the highsurface area amorphous silica is present in the fluid loss controladditive in an amount sufficient to provide a desired after-setcompressive strength.
 32. The method of claim 28 wherein the highsurface area amorphous silica is present in the fluid loss controladditive in an amount in the range of from about
 0. 1% to about 15% byweight of the fluid loss control additive.
 33. The method of claim 1wherein the acrylamide copolymer derivative is present in the fluid losscontrol additive in an amount in the range of from about 1% to about 99%by weight.
 34. The method of claim 2 wherein the copolymer or copolymersalt has a N,N-dimethylacrylamide to 2-acrylamido-2-methylpropanesulfonic acid (or acid salts thereof) mole ratio of from about 1:4 toabout 4:1.
 35. The method of claim 2 wherein the copolymer or copolymersalt has a weight average molecular weight of between about 75,000 andabout 300,000 daltons.
 36. The method of claim 10 wherein the zeolitefurther comprises chabazite and amorphous silica.
 37. The method ofclaim 10 wherein the zeolite is present in the fluid loss controladditive in an amount in the range of from about 0 1% to about 15% byweight of the fluid loss control additive.
 38. The method of claim 1wherein the fluid loss control additive is present in the cementcomposition in an amount in the range of from about 0.25% to about 1.5%by weight of the cement; wherein the hydratable polymer is present inthe fluid loss control additive in an amount in the range of from about1.5% to about 4.5% by weight; wherein the acrylamide copolymerderivative is present in the fluid loss control additive in an amount inthe range of from about 40% by weight to about 50% by weight; whereinthe dispersing agent is present in the fluid loss control additive in anamount in the range of from about in the range of from about 40% toabout 60% by weight; wherein the zeolite is present in the fluid losscontrol additive in an amount in the range of from about 1% by weight toabout 10% by weight.
 39. A method of cementing in a subterraneanformation comprising the steps of: providing a cement compositioncomprising a hydraulic cement, water, and a fluid loss control additive,the fluid loss control additive comprising: an acrylamide copolymerderivative; and a dispersant; placing the cement composition into thesubterranean formation; and permitting the cement composition to settherein.
 40. The method of claim 39 wherein the acrylamide copolymerderivative comprises a copolymer or copolymer salt ofN,N-dimethylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid oracid salts thereof.
 41. The method of claim 39 wherein the acrylamidecopolymer derivative comprises a graft polymer comprising a backbonecomprising at least one member selected from the group consisting oflignin, lignite and their salts and a grafted pendant group comprisingat least one member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 42. Themethod of claim 39 wherein the acrylamide copolymer derivative comprisesa graft polymer comprising a backbone comprising at least one memberselected from the group consisting of derivatized cellulose, polyvinylalcohol, polyethylene oxide, polypropylene oxide, and a grafted pendantgroup comprising at least one member selected from the group consistingof 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 43. Themethod of claim 39 wherein the acrylamide copolymer derivative comprisescopolymers or copolymer salts comprising 2-acrylamido-2-methylpropanesulfonic acid or acid salts thereof.
 44. The method of claim 43 whereinthe copolymers or copolymer salts comprise copolymers of hydrolyzedacrylamide and 2-acrylamido-2-methylpropane sulfonic acid derivatives.45. The method of claim 39 wherein the fluid loss control additivefurther comprises a hydratable polymer and zeolite.
 46. A method ofreducing the fluid loss from a cement composition, comprising the stepof adding to the cement composition a fluid loss control additivecomprising: an acrylamide copolymer derivative; and a hydratablepolymer.
 47. The method of claim 46 wherein the acrylamide copolymerderivative comprises a copolymer or copolymer salt ofN,N-dimethylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid oracid salts thereof.
 48. The method of claim 46 wherein the acrylamidecopolymer derivative comprises a graft polymer comprising a backbonecomprising at least one member selected from the group consisting oflignin, lignite and their salts and a grafted pendant group comprisingat least one member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 49. Themethod of claim 46 wherein the acrylamide copolymer derivative comprisesa graft polymer comprising a backbone comprising at least one memberselected from the group consisting of derivatized cellulose, polyvinylalcohol, polyethylene oxide, polypropylene oxide, and a grafted pendantgroup comprising at least one member selected from the group consistingof 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 50. Themethod of claim 46 wherein the acrylamide copolymer derivative comprisescopolymers or copolymer salts comprising 2-acrylamido-2-methylpropanesulfonic acid or acid salts thereof.
 51. The method of claim 50 whereinthe copolymers or copolymer salts comprise copolymers of hydrolyzedacrylamide and 2-acrylamido-2-methylpropane sulfonic acid derivatives.52. The method of claim 46 wherein the hydratable polymer comprisescarboxymethylcellulose, hydroxyethylcellulose,carboxymethylhydroxyethylcellulose, vinyl sulfonated polymers,hydratable graft polymers, and mixtures thereof.
 53. The method of claim46 wherein the fluid loss control additive further comprises adispersant.
 54. The method of claim 53 wherein the dispersant comprisesa water-soluble polymer prepared by the caustic-catalyzed condensationof formaldehyde with acetone wherein the polymer contains sodium sulfategroups.
 55. The method of claim 46 wherein the fluid loss controladditive further comprises a zeolite.
 56. The method of claim 46 whereinthe fluid loss control additive further comprises a dispersant and azeolite.
 57. The method of claim 56 wherein the fluid loss controladditive further comprises iron chloride, an organic acid, adeaggregation agent, silica, or mixtures thereof.
 58. The method ofclaim 46 wherein the cement composition comprises Portland cements,pozzolanic cements, gypsum cements, high alumina content cements, silicacements, or high alkalinity cements.
 59. The method of claim 46 whereinthe cement composition comprises water present in an amount sufficientto form a pumpable slurry.
 60. The method of claim 59 wherein the wateris present in the cement composition in an amount in the range of fromabout 15% by weight of cement to about 200% by weight of cement.
 61. Themethod of claim 46 wherein the cement composition has a density in therange of from about 5 pounds per gallon to about 30 pounds per gallon.62. The method of claim 46 wherein the cement composition furthercomprises a weighting agent, a defoamer, a surfactant, mica, fiber,bentonite, microspheres, fumed silica, a salt, vitrified shale, fly ash,a dispersant, a retardant or an accelerant.
 63. The method of claim 46wherein the fluid loss control additive is present in the cement,composition in an amount sufficient to provide a desired degree of fluidloss control.
 64. The method of claim 46 wherein the fluid loss controladditive is present in the cement composition in an amount in the rangeof from about 0.01% by weight of cement to about 5.0% by weight ofcement.
 65. The method of claim 57 wherein the iron chloride is presentin the fluid loss control additive in an amount sufficient to allow thecement to be suitable for the subterranean temperature of the well beingcemented.
 66. The method of claim 57 wherein the iron chloride ispresent in the fluid loss control additive in an amount in the range offrom about 5% to about 25% by weight of the fluid loss control additive.67. The method of claim 57 wherein the iron chloride is anhydrous ferricchloride.
 68. The method of claim 53 wherein the dispersant is presentin the fluid loss control additive in an amount sufficient to preventgelation of the cement composition.
 69. The method of claim 53 whereinthe dispersant is present in the fluid loss control additive in anamount in the range of from about 25% to about 50% by weight of thefluid loss control additive.
 70. The method of claim 46 wherein thehydratable polymer is present in the fluid loss control additive in anamount in the range of from about 0.1% to about 15% by weight of thefluid loss control additive.
 71. The method of claim 57 wherein theorganic acid is present in the fluid loss control additive in an amountsufficient to provide a desired degree of viscosity control.
 72. Themethod of claim 57 wherein the organic acid is present in the fluid losscontrol additive in an amount in the range of from about 0.01% to about5% by weight of the fluid loss control additive.
 73. The method of claim57 wherein the silica is high surface area amorphous silica.
 74. Themethod of claim 57 wherein the de-aggregation agent is present in thefluid loss control additive in an amount sufficient to enable the fluidloss control additive to flow freely as a powder.
 75. The method ofclaim 57 wherein the de-aggregation agent is present in the fluid losscontrol additive in an amount in the range of from about 1% to about 15%by weight of the fluid loss control additive.
 76. The method of claim 73wherein the high surface area amorphous silica is present in the fluidloss control additive in an amount sufficient to provide a desiredafter-set compressive strength.
 77. The method of claim 73 wherein thehigh surface area amorphous silica is present in the fluid loss controladditive in an amount in the range of from about 0.1% to about 15% byweight of the fluid loss control additive.
 78. The method of claim 46wherein the acrylamide copolymer derivative is present in the fluid losscontrol additive in an amount in the range of from about 1% to about 99%by weight.
 79. The method of claim 47 wherein the copolymer or copolymersalt has a N,N-dimethylacrylamide to 2-acrylamido-2-methylpropanesulfonic acid (or acid salts thereof) mole ratio of from about 1:4 toabout 4:1.
 80. The method of claim 47 wherein the copolymer or copolymersalt has a weight average molecular weight of between about 75,000 andabout 300,000 daltons.
 81. The method of claim 55 wherein the zeolitefurther comprises chabazite and amorphous silica.
 82. The, method ofclaim 55 wherein the zeolite is present in the fluid loss controladditive in an amount in the range of from about 0.1% to about 15% byweight.
 83. The method of claim 46 wherein the fluid loss controladditive is present in the cement composition in an amount in the rangeof from about 0.25% to about 1.5% by weight of the cement; wherein thehydratable polymer is present in the fluid loss control additive in anamount in the range of from about 1.5% to about 4.5% by weight; whereinthe acrylamide copolymer derivative is present in the fluid loss controladditive in an amount in the range of from about.40% by weight to about50% by weight; wherein the dispersing agent is present in the fluid losscontrol additive in an amount in the range of from about in the range offrom about 40% to about 60% by weight; wherein the zeolite is present inthe fluid loss control additive in an amount in the range of from about1% by weight to about 10% by weight.
 84. A method of reducing the fluidloss from a cement composition, comprising the step of adding to thecement composition a fluid loss control additive comprising: anacrylamide copolymer derivative; and a dispersant.
 85. The method ofclaim 84 wherein the acrylamide copolymer derivative comprises acopolymer or copolymer salt of N,N-dimethylacrylamide and2-acrylamido-2-methylpropane sulfonic acid or acid salts thereof. 86.The method of claim 84 wherein the acrylamide copolymer derivativecomprises a graft polymer comprising a backbone comprising at least onemember selected from the group consisting of lignin, lignite and theirsalts and a grafted pendant group comprising at least one memberselected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 87. Themethod of claim 84 wherein the acrylamide copolymer derivative comprisesa graft polymer comprising a backbone comprising at least one memberselected from the group consisting of derivatized cellulose, polyvinylalcohol polyethylene oxide, polypropylene oxide, and a grafted pendantgroup comprising at least one member selected from the group consistingof 2-acrylamido-2-methylprop anesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 88. Themethod of claim 84 wherein the acrylamide copolymer derivative comprisescopolymers or copolymer salts comprising 2-acrylamido-2-methylpropanesulfonic acid or acid salts thereof.
 89. The method of claim 88 whereinthe copolymers or copolymer salts comprise copolymers of hydrolyzedacrylamide and 2-acrylamido-2-methylpropane sulfonic acid derivatives.90. The method of claim 84 wherein the fluid loss control additivefurther comprises a hydratable polymer and zeolite.
 91. A cementcomposition comprising a hydraulic cement, water, and a fluid losscontrol additive, the fluid loss control additive comprising: anacrylamide copolymer derivative; and a hydratable polymer.
 92. Thecement composition of claim 91 wherein the acrylamide copolymerderivative comprises a copolymer or copolymer salt ofN,N-dimethylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid oracid salts thereof.
 93. The cement composition of claim 91 wherein theacrylamide copolymer derivative comprises a graft polymer comprising abackbone comprising at least one member selected from the groupconsisting of lignin, lignite and their salts and a grafted pendantgroup comprising at least one member selected from the group consistingof 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 94. Thecement composition of claim 91 wherein the acrylamide copolymerderivative comprises a graft polymer comprising a backbone comprising atleast one member selected from the group consisting of derivatizedcellulose, polyvinyl alcohol, polyethylene oxide, polypropylene oxide,and a grafted pendant group comprising at least one member selected fromthe group consisting of 2-acrylamido-2-methylpropanesulfonic acid,acrylonitrile, N,N-dimethylacrylamide, acrylic acid,N,N-dialkylaminoethylmethacrylate wherein the alkyl radical comprises atleast one member selected from the group consisting of methyl, ethyl andpropyl radicals.
 95. The cement composition of claim 91 wherein theacrylamide copolymer derivative comprises copolymers or copolymer saltscomprising 2-acrylamido-2-methylpropane sulfonic acid or acid saltsthereof.
 96. The cement composition of claim 95 wherein the copolymersor copolymer salts comprise copolymers of hydrolyzed acrylamide and2-acrylamido-2-methylpropane sulfonic acid derivatives.
 97. The cementcomposition of claim 91 wherein the hydratable polymer comprisescarboxymethylcellulose, hydroxyethylcellulose,carboxymethylhydroxyethylcellulose, vinyl sulfonated polymers,hydratable graft polymers, and mixtures thereof.
 98. The cementcomposition of claim 91 wherein the fluid loss control additive furthercomprises a dispersant.
 99. The cement composition of claim 98 whereinthe dispersant comprises a water-soluble polymer prepared by thecaustic-catalyzed condensation of formaldehyde with acetone wherein thepolymer contains sodium sulfate groups.
 100. The cement composition ofclaim 91 wherein the fluid loss control additive further comprises azeolite.
 101. The cement composition of claim 91 wherein the fluid losscontrol additive further comprises a dispersant and a zeolite.
 102. Thecement composition of claim 101 wherein the fluid loss control additivefurther comprises iron chloride, an organic acid, a deaggregation agent,silica, or mixtures thereof.
 103. The cement composition of claim 91wherein the hydraulic cement comprises Portland cements, pozzolaniccements, gypsum cements, high alumina content cements, silica cements,or high alkalinity cements.
 104. The cement composition of claim 91wherein the water is present in the cement composition in an amountsufficient to form a pumpable slurry.
 105. The cement composition ofclaim 91 wherein the water is present in the cement composition in anamount in the range of from about 15% by weight of cement to about 200%by weight of cement.
 106. The cement composition of claim 91 wherein thecement composition has a density in the range of from about 5 pounds pergallon to about 30 pounds per gallon.
 107. The cement composition ofclaim 91 wherein the cement composition further comprises a weightingagent, a defoamer, a surfactant, mica, fiber, bentonite, microspheres,fumed silica, a salt, vitrified shale, fly ash, a dispersant, aretardant or an accelerant.
 108. The cement composition of claim 91wherein the fluid loss control additive is present in the cementcomposition in an amount sufficient to provide a desired degree of fluidloss control.
 109. The cement composition of claim 91 wherein the fluidloss control additive is present in the cement composition in an amountin the range of from about 0.01% by weight of cement to about 5.0% byweight of cement.
 110. The cement composition of claim 102 wherein theiron chloride is present in the fluid loss control additive in an amountsufficient to allow the cement to be suitable for the subterraneantemperature of the well being cemented.
 111. The cement composition ofclaim 102 wherein the iron chloride is present in the fluid loss controladditive in an amount in the range of from about 5% to about,25% byweight of the fluid loss control additive.
 112. The cement compositionof claim 102 wherein the iron chloride is anhydrous ferric chloride.113. The cement composition of claim 98 wherein the dispersant ispresent in the fluid loss control additive in an amount sufficient toprevent gelation of the cement composition.
 114. The cement compositionof claim 98 wherein the dispersant is present in the fluid loss controladditive in an amount in the range of from about 25% to!about 50% byweight of the fluid loss control additive.
 115. The cement compositionof claim 91 wherein the hydratable polymer is present in the fluid losscontrol additive in an amount in the range of from about 0.1% to about15% by weight of the fluid loss control additive.
 116. The cementcomposition of claim 102 wherein the organic acid is present in thefluid loss control additive in an amount sufficient to provide a desireddegree of viscosity control.
 117. The cement composition of claim 102wherein the organic acid is present in the fluid loss control additivein an amount in the range of from about 0.01% to about 5% by weight ofthe fluid loss control additive.
 118. The cement composition of claim102 wherein the silica is high surface area amorphous silica.
 119. Thecement composition of claim 102 wherein the de-aggregation agent ispresent in the fluid loss control additive in an amount sufficient toenable the fluid loss control additive to flow freely as a powder. 120.The cement composition of claim 102 wherein the de-aggregation agent ispresent in the fluid loss control additive in an amount in the range offrom about 1% to about 15% by weight of the fluid loss control additive.121. The cement composition of claim 118 wherein the high surface areaamorphous silica is present in the fluid loss control additive in anamount sufficient to provide a desired after-set compressive strength.122. The cement composition of claim 118 wherein the high surface areaamorphous silica is present in the fluid loss control additive in anamount in the range of from about 0.1% to about 15% by weight of thefluid loss control additive.
 123. The cement composition of claim 91wherein the acrylamide copolymer derivative is present in the fluid losscontrol additive in an amount in the range of from about 1% to about 99%by weight.
 124. The cement composition of claim 92 wherein the copolymeror copolymer salt has a N,N-dimethylacrylamide to2-acrylamido-2-methylpropane sulfonic acid (or acid salts thereof) moleratio of from about 1:4 to about 4:1.
 125. The cement composition ofclaim 92 wherein the. copolymer or copolymer salt has a weight averagemolecular weight of between about 75,000 and about 300,000 daltons. 126.The cement composition of claim 100 wherein the zeolite furthercomprises chabazite and amorphous silica.
 127. The cement composition ofclaim 100 wherein the zeolite is present in the fluid loss controladditive in an amount in the range of from about 0.1% to about 15% byweight of the fluid loss control additive.
 128. The cement compositionof claim 91 wherein the fluid loss control additive is present in thecement composition in an amount in the range of from about 0.25% toabout 1.5% by weight of the cement; wherein the hydratable polymer ispresent in the fluid loss control additive in an amount in the range offrom about 1.5% to about 4.5% by weight; wherein the acrylamidecopolymer derivative is present in the fluid loss control additive in anamount in the range of from about 40% by weight to about 50% by weight;wherein the dispersing agent is present in the fluid loss controladditive in an amount in the range of from about in the range of fromabout 40% to about 60% by weight; wherein the zeolite is present in thefluid loss control additive in an amount in the range of from about 1%by weight to about 10% by weight.
 129. A cement composition comprising ahydraulic cement, water, and a fluid loss control additive, the fluidloss control additive comprising: an acrylamide copolymer derivative;and a dispersant.
 130. The cement composition of claim 129 wherein theacrylamide copolymer derivative comprises a copolymer or copolymer saltof N,N-dimethylacrylamide and 2-acrylamido-2-methylpropane sulfonic acidor acid salts thereof.
 131. The cement composition of claim 129 whereinthe acrylamide copolymer derivative comprises a graft polymer comprisinga backbone comprising at least one member selected from the groupconsisting of lignin, lignite and their salts and a grafted pendantgroup comprising at least one member selected from the group consistingof 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 132. Thecement composition of claim 129 wherein the acrylamide copolymerderivative comprises a graft polymer comprising a backbone comprising atleast one member selected from the group consisting of derivatizedcellulose,. polyvinyl alcohol,. polyethylene oxide, polypropylene oxide,and a grafted pendant group comprising at least one member selected fromthe group consisting of 2-acrylamido-2-methylpropanesulfonic acid,acrylonitrile, N,N-dimethylacrylamide, acrylic acid,N,N-dialkylaminoethylmethacrylate wherein the alkyl radical comprises atleast one member selected from the group consisting of methyl, ethyl andpropyl radicals.
 133. The cement composition of claim 129 wherein theacrylamide copolymer derivative comprises copolymers or copolymer saltscomprising 2-acrylamido-2-methylpropane sulfonic acid or acid saltsthereof.
 134. The cement composition of claim 133 wherein the copolymersor copolymer salts comprise copolymers of hydrolyzed acrylamide and2-acrylamido-2-methylpropane sulfonic acid derivatives.
 135. The cementcomposition of claim 129 wherein the fluid loss control additive furthercomprises a hydratable polymer and zeolite.
 136. A fluid loss controladditive comprising: an acrylamide copolymer derivative; and ahydratable polymer.
 137. The fluid loss control additive of claim 136wherein the acrylamide copolymer derivative comprises a copolymer orcopolymer salt of N,N-dimethylacrylamide and2-acrylamido-2-methylpropane sulfonic acid or acid salts thereof. 138.The fluid loss control additive of claim 136 wherein the acrylamidecopolymer derivative comprises a graft polymer comprising a backbonecomprising at least one member selected from the group consisting oflignin, lignite and their salts and a grafted pendant group comprisingat least one member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylamninoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 139. Thefluid loss control additive of claim 136 wherein the acrylamidecopolymer derivative comprises a graft polymer comprising a backbonecomprising at least one member selected from the group consisting ofderivized cellulose, polyvinyl alcohol, polyethylene oxide,polypropylene oxide, and a grafted pendant group comprising at leastone, member selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid,_acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 140. Thefluid loss control additive of claim 136 wherein the acrylamidecopolymer derivative comprises copolymers or copolymer salts comprising2-acrylamido-2-methylpropane sulfonic acid or acid salts thereof. 141.The fluid loss control additive of claim 140 wherein the copolymers orcopolymer salts comprise copolymers of hydrolyzed acrylamide and2-acrylamido-2-methylpropane sulfonic acid derivatives.
 142. The fluidloss control additive of claim 136 wherein the hydratable polymercomprises carboxymethylcellulose, hydroxyethylcellulose,carboxymethylhydroxyethylcellulose, vinyl sulfonated polymers,hydratable graft polymers, and mixtures thereof.
 143. The fluid losscontrol additive of claim 136 further comprising a dispersant.
 144. Thefluid loss control additive of claim 143 wherein the dispersantcomprises a water-soluble polymer prepared by the caustic-catalyzedcondensation of formaldehyde with acetone wherein the polymer containssodium sulfate groups.
 145. The fluid loss control additive of claim 136further comprising a zeolite.
 146. The fluid loss control additive ofclaim 136 further comprising a dispersant and a zeolite.
 147. The fluidloss control additive of claim 146 further comprising iron chloride, anorganic acid, a deaggregation agent, silica, or mixtures thereof. 148.The fluid loss control additive of claim 147 wherein the iron chlorideis present in an amount sufficient to allow a cement composition to besuitable for the subterranean temperature of the well being cemented.149. The fluid loss control additive of claim 147 wherein the ironchloride is present in an amount in the range of from about 5% to about25% by weight of the fluid loss control additive.
 150. The fluid losscontrol additive of claim 147 wherein the iron chloride is anhydrous;ferric chloride.
 151. The fluid loss control additive of claim 143wherein the dispersant is present in an amount sufficient to preventgelation of a cement composition.
 152. The fluid loss control additiveof claim 143 wherein the dispersant is present in an amount in the rangeof from about 25% to about 50% by weight of the fluid loss controladditive.
 153. The fluid loss control additive of claim 136 wherein thehydratable polymer is present in an amount in the range of from about0.1% to about 15% by weight of the fluid loss control additive.
 154. Thefluid loss control additive of claim 147 wherein the organic acid ispresent in an amount sufficient to provide a desired degree of viscositycontrol.
 155. The fluid loss control additive of claim 147 wherein theorganic acid is present in an amount in the range of from about 0.01% toabout 5% by weight of the fluid loss control additive.
 156. The fluidloss control additive of claim 147 wherein the silica is high surfacearea amorphous silica.
 157. The fluid loss control additive of claim 147wherein the de-aggregation agent is present in an amount sufficient toenable the fluid loss control additive to flow freely as a powder. 158.The fluid loss control additive of claim 147 wherein the de-aggregationagent is present in an amount in the range of from about 1% to about 15%by weight of the fluid loss control additive.
 159. The fluid losscontrol additive of claim 156 wherein the high surface area amorphoussilica is present in an amount sufficient to provide a desired after-setcompressive strength.
 160. The fluid loss control additive of claim 156wherein the high surface area amorphous silica is present in an amountin the range of from about 0.1% to about 15% by weight of the fluid losscontrol additive.
 161. The fluid loss control additive of claim 136wherein the acrylamide copolymer derivative is present in an amount inthe range of from about 1% to about 99% by weight.
 162. The fluid losscontrol additive of claim 137 wherein the copolymer or copolymer salthas a N,N-dimethylacrylamide to 2-acrylamido-2-methylpropane sulfonicacid (or acid salts thereof) mole ratio of from about 1:4 to about 4:1.163. The fluid loss control additive of claim 137 wherein the copolymeror copolymer salt has a weight average molecular weight of between about75,000, and about 300,000 daltons.
 164. The fluid loss control additiveof claim 145 wherein the zeolite further comprises chabazite andamorphous silica.
 165. The fluid loss control additive of claim 145wherein the zeolite is present in an amount in the range of from about0.1% to about 15% by weight.
 166. The fluid loss control additive ofclaim 136 wherein the fluid loss control additive is present in thecement composition in an amount in the range of from about 0.25% toabout 1.5% by weight of the cement; wherein the hydratable polymer ispresent in the fluid loss control additive in an amount in the range offrom about 1.5% to about 4.5% by weight; wherein the acrylamidecopolymer derivative is present in the fluid loss control additive in anamount in the range of from about 40% by weight to about 50% by weight;wherein the dispersing agent is present in the fluid loss controladditive in an amount in the range of from about in the range of fromabout 40% to about 60% by weight; wherein the zeolite is present in thefluid loss control additive in an amount in the range of from about 1%by weight to about 10% by weight.
 167. A fluid loss control additivecomprising: an acrylamide copolymer derivative; and a dispersant. 168.The fluid loss control additive of claim 167 wherein the acrylamidecopolymer derivative comprises a copolymer or copolymer salt ofN,N-dimethylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid oracid salts thereof.
 169. The fluid loss control additive of claim 167wherein the acrylamide copolymer derivative comprises a graft polymercomprising a backbone comprising at least one member selected from thegroup consisting of lignin, lignite and their salts and a graftedpendant group comprising at least one member, selected from the groupconsisting of 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 170. Thefluid loss control additive of claim 167 wherein the acrylamidecopolymer derivative comprises a graft polymer comprising a backbonecomprising at least one member selected from the group consisting ofderivatized cellulose, polyvinyl alcohol, polyethylene oxide,polypropylene oxide, and a grafted pendant group comprising at least onemember selected from the group consisting of2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile,N,N-dimethylacrylamide, acrylic acid, N,N-dialkylaminoethylmethacrylatewherein the alkyl radical comprises at least one member selected fromthe group consisting of methyl, ethyl and propyl radicals.
 171. Thefluid loss control additive of claim 167 wherein the acrylamidecopolymer derivative comprises copolymers or copolymer salts comprising2-acrylamido-2-methylpropane sulfonic acid or acid salts thereof. 172.The fluid loss control additive of claim 171 wherein the copolymers orcopolymer salts comprise copolymers of hydrolyzed acrylamide and2-acrylamido-2-methylpropane sulfonic acid derivatives.
 173. The fluidloss control additive of claim, 167 further comprising a hydratablepolymer and a zeolite.
 174. The fluid loss control additive of claim 167wherein the dispersant comprises a water-soluble polymer prepared by thecaustic-catalyzed condensation of formaldehyde with acetone wherein thepolymer contains sodium sulfate groups.